This was a key government demand to end its ban.
Twitter says it has “established a legal entity in Nigeria”, months after the social media firm agreed to conditions set out by the government for its service to be restored in the country.
Nigeria suspended the microblogging site last June after a tweet by President Muhammadu Buhari, that referenced the civil war, was deleted.
Twitter had said the post violated its rules; the government accused the company of taking sides.
The seven-month ban was lifted in January after Twitter agreed to various conditions, one of which was that it register in Nigeria before March.
A Twitter representative confirmed to the BBC that the company now had a legal presence in Nigeria but did not state when this had happened.
The company also told the BBC that it was complying with tax obligations in Nigeria, as it does globally.
Last year, Twitter announced that it was opening its African headquarters in Ghana and has since filled advertised roles.
The company has been in the news recently after its board agreed to a $44bn (£34.5bn) takeover offer from the billionaire Elon Musk.